math help

What is 80/2 + 2/5?

What is 80/2 + 2/5?

Here's how you add

80
2
+
2
5

Step 1

We still have different denominators (bottom numbers), though, so we need to get a common denominator. This will make the bottom numbers match. Multiply the denominators together first. Now, multiply each numerator by the other term's denominator.

Now we multiply 80 by 5, and get 400, then we multiply 2 by 5 and get 10.

80/2 times 5

Now for the second term. You multiply 2 by 2, and get 4, then multiply 2 by 5 and get 10.

2/5 times 2

This gives us a new problem that looks like so:

400
10
+
4
10

Step 2

Since our denominators match, we can add the numerators.

400 + 4 = 404

That gives us an answer of

404
10

Step 3

Can this fraction be reduced?

First, we attempt to divide it by 2...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

404
10
÷ 2 =
202
5

So far so good... let's try to divide by that number again.

No good. So next you try the next prime number, which is 3...

No good. So next you try the next prime number, which is 5...

No good. So next you try the next prime number, which is 7...

No good. 7 is larger than 5. So we're done reducing.

And we're done! Here's the final answer to 80/2 + 2/5

80
2
+
2
5
=
202
5
© 2014 Randy Tayler